1. Field of the Invention
One embodiment of the present invention relates to a memory device.
2. Description of the Related Art
In recent years, memory devices capable of rewriting data have been developed.
As an example of such memory devices, a content addressable memory can be given.
The content addressable memory is a memory device capable of identifying data stored in a memory cell with respect to search data, in addition to rewriting data.
The content addressable memory is used for a set-associative cache memory for example. The set-associative structure is a data storage structure including a plurality of tags, and a content addressable memory is used as each of the tags. The use of the content addressable memory for the cache memory can increase the data communication speed between a CPU and the cache memory.
A memory cell in a content addressable memory includes, for example, a memory circuit which holds data and a plurality of comparison circuits which compare the data stored in the memory circuit with specific data (e.g., Patent Document 1).
In Patent Document 1, multi-bit data can also be identified by a level comparison circuit and a match detection circuit.